U.S. Pat. No. 4,787,672 of Werner describes a free-swinging chair having an angular seating portion having a seat and a backrest, both configured as one common component. A chair frame for supporting the seating portion has two lateral components having a tubular profile that is bent into an almost Z-type shape to achieve a spring-like effect. To avoid an excess swinging and/or rocking action of the chair, a bar-shaped reinforcement member is disposed on both lateral components, connecting the two end sections of the respective Z-shaped components. In this configuration, any excess sizing of the bent tubular profile can be avoided which, aside from an increase in weight, would also reduce the spring action.
German App. No. DE 41 35 488 A1 of Landgraf describes one means for avoiding excess sizing of the bent tubular profile. For example, Landgraf proposes inserting reinforcement members into the tubular profile before the bending process, which are then subsequently deformed together with the tubular profile and thus contribute to a reinforcement of the profile. However, a reinforcement of this kind runs counter to a desired spring action.
German App. No. DE 297 18 785 U1 of Erhard discloses a chair construction with an immobile seating area and a free-swinging backrest that swings independently of the seating area. The chair frame is constructed of square-steel-bar tubing including two arc-type constructs for holding the backrest in the bottom area of the base points and in the upper area of the backrest.
Accordingly, the present inventors have identified a need for seating furniture having a frame and a free-swinging seat and backrest, where both the seat and backrest swing freely and independently of each other. In addition, the present inventors have identified a need for such a seating furniture that helps avoid excess sizing of the frame.